The invention makes use of so-called "action paper" which is a well-known type of paper and which has a surface coating of dye capsules that, upon impact or rupture, give an impression upon a contacting sheet of paper. Such action paper can be purchased in the U.K. from Wiggins, Teape Limited. Such action paper is available in a variety of forms and is sometimes known as carbonless copy paper or self-copying paper.
Action paper enables a copy to be readily made of information placed upon it by writing, typing or the like, without the need for separate sheets of carbon paper. Action paper is often used for multiple business forms where several copies of all written or typed information are required. For instance, the top sheet of an invoice is given to the customer and successive copies of the invoice are required for stock control records, internal accounting systems and general house files and the like. Clearly, a number of identical sheets of action paper could be arranged in a stack and the information placed by the user on the top sheet. Usually, however, the appearance of the action paper is such tht it does not appeal as a top sheet suitable for giving to the customer and it is usual to employ a better quality paper for the top sheet that is eventually handed to the customer.
It has been the practice heretofore to print the same information on each sheet of the action paper as is present on the top sheet, i.e. the letter heading and other standard information. In this case, the stacks of action paper, each with a top sheet of good appearance, have to be prepared for each user and thereby a limited number of each stack is required.
It is much more efficient if the action paper is plain and does not carry the printed matter present on the top sheet as this means that the stacks of action paper are the same for all users.